Galvanometer to ammeter/voltmeter

  • #1

Homework Statement



The resistance of a galvanometer coil is 25ohms and the current required for full scale deflection is 500μA.
a) explain how to convert the galvanometer to an ammeter reading 20mA full scale, and compute the shunt resistance
b) explain how to convert the galvanometer to a voltmeter reading 500mV full scale, compute the series resistance

Homework Equations



V=IR
IfsRG= (Ia-Ifs)Rsh
Rsh=(RGIfs)/(Ia-Ifs)


The Attempt at a Solution




RG=25ohms

a)
does Ifs=0.02 or 0.0005A

0.0005A * 25ohms = ( 0.02A- 0.0005A) Rsh ??
Rsh=0.641

b)
 
Last edited:

Answers and Replies

  • #2
gneill
Mentor
20,875
2,838
Your value for (a) looks okay. How will you approach (b)?
 
  • #3
idk VV=Ifs(Rsh+Rh)
 
  • #4
(0.5/0.0005) -25 = 975 ?
 
  • #5
gneill
Mentor
20,875
2,838
Looks good.
 
  • #6
cool beans
 

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